Nicky Henderson may be six days from securing his status as the champion jumps trainer, thanks to Shakalakaboomboom, who has an excellent chance in Saturday's Grand National. The Lambourn trainer, now 61, has not held the title for a quarter of a century, but he has never been more successful than in the present season and welcomed a record seven winners back from last month's Cheltenham Festival.

Even so, he is engaged in a close battle with the reigning champion, Paul Nicholls, but the National carries first-place prize money of more than £500,000 and victory for either man would end the fight. Neither has won the Aintree race and Henderson has had very few runners in recent years, but Shakalakaboomboom looks the right type for such a severe test. In contrast to most of his stablemates, speed has never been this one's forte. He was a stranger to the winner's enclosure until being sent over fences and three of his four successes have come at distances beyond three miles.

He had a spin over these fences in the Topham Chase last April and jumped well, though the trip was on the short side for him and he was well beaten. But he showed his doughty side at Punchestown the next month, recovering from a last-fence mistake to recover the lead close home.

Sent to Cheltenham in December, Shakalakaboomboom again scored an impressive win. He has since been beaten twice, in contests with insufficient emphasis on stamina. "Look, those were just to get him to Aintree," Henderson reassured me on Saturday. He is pleased with the horse's condition.

At eight years old and having been a novice last year, Shakalakaboomboom is on the inexperienced side for this race, but few with his profile have been so likely to benefit from the race's conditions. He has just less than 11st to carry, placing him right at that section of the weights from which most winners emerge.

From a trends perspective, few races are so reliable as the National and it remains extremely challenging for horses with more than 11 stone on their backs. Red Rum in 1977 was the last winner who shouldered more than 11st 5lb. Of all those burdened with 11st 2lb or more since 1983, just one has been successful.

In that context, it is hard to be enthusiastic about the chances of Synchronised, trying to be the second horse to win the National in the same season as the Cheltenham Gold Cup. Allotted 11st 10lb, he will have to be one of the all-time greats to get home in front. Just one mistake like the one he made at the first fence last month will end his chance. Ballabriggs has just 1lb less, but his credentials are more obvious in light of his victory in the last National, when he floated over most of these fences. It is common for previous winners to run well under crushing burdens the following year and he should be placed, though there will probably be something quicker up the run-in.

Mon Mome, a shock winner in 2009, is once more available at three-figure odds and I have been sweet on his chances since he was a respectable second at Cheltenham on New Year's Day. Alas, the form of that race has not worked out well and he was probably flattered. I may regret saying so but it seems likely his best days are behind him. Those with more evident claims include Planet Of Sound, a former Grade One winner who has been placed in the Hennessy and the Racing Post Chase this winter, though he is desperately short of pace and has plenty of weight. According To Pete is also easy to like, though he probably needs the going to be softer than is likely.

Always Right has had his soft palate cauterised since he was pulled up in his last two starts, while a similar operation may help Killyglen get through the race better than last year, when he was a late faller after back-to-back mistakes.

But the most attractive each-way option is Quiscover Fontaine, a staying-on fourth in last year's Irish National, who has been running well in two-mile hurdles but may be better suited by these conditions. Abbeybraney is no wacky outsider, having gone close at Grade One level early in his career. Injuries have limited him, but he showed renewed promise last time and has dropped to a nice weight. The Borders trainer George Bewley tells me he has progressed at home and is an intended runner, though he may not quite make the cut at the final declaration stage on Thursday.

Ruby Walsh chooses to ride On His Own

On His Own was the big mover in betting on the Grand National on Saturday as news emerged that he was the choice of Ruby Walsh, who has twice ridden the winner of the Aintree race. Walsh picked the horse in preference to The Midnight Club, Neptune Collonges and Seabass.

Bookmakers reacted by cutting the eight-year-old to 14-1 from 20-1 and anticipate further support. "If you look at the last five years, Ruby's mount has generally ended up as the first- or second-favourite," said Betfred's George Primarolo. "Had it not been for the presence of Synchronised in the race, On His Own might well have become favourite."

Writing in the Irish Examiner, Walsh said he would not have felt comfortable choosing Seabass, trained by his father, Ted, over horses based with his established employers, Willie Mullins and Paul Nicholls. But he expressed a concern that On His Own had shown his best form on right-handed circuits and may not cope so well with left-handed Aintree. That fear is not shared by Mullins, who intends to field him and at least two others in the race. Reporting that On His Own had been working well in the past week, he pointed out that the horse had won at left-handed Ayr last spring.

Mullins said he had diverted Quiscover Fontaine to Aintree after it became clear that he would have had a lot of weight to carry in Monday's Irish National. He said that The Midnight Club had been improving in his home work but would need to do even better in order to leave his poor recent form behind.

Apt Approach may also run for Mullins on Saturday but he has an alternative engagement in the shorter Topham Chase on Friday. Quel Esprit is likely to be saved for the Punchestown Festival.

Walsh's choice left the way clear for his sister, Katie, to be given the ride on Seabass, as was also confirmed yesterday. Daryl Jacob is expected to ride Neptune Collonges.

Donald McCain announced that Weird Al is now an intended runner, having "looked in great nick at home" since bursting a blood vessel in last month's Cheltenham Gold Cup. Timmy Murphy will ride.